This invention relates to an optical signal reproducing apparatus, for a disc phonograph record, which will simply be called a record hereinafter.
Usual apparatus that reproduces signals from a record utilizes a stylus pickup. Inherent to this technique, there are many problems such as wear, distortion, and noise transients from scratches. An optical signal reproducing apparatus that reproduces signals with no contact to the record can avoid such problems. But, optical signal reproducing apparatus that have been proposed include new problems as follows. It is difficult to achieve high fidelity when a light beam irradiates the surface of the groove from a certain direction, because the signal that has been detected from variations of the reflected light beam is not proportional to the recorded signal. Besides in the apparatus which reproduces signals directly from the variations of the detected light, it is inevitable that the fluctuation in the reflexibility of the surface of the groove and the fluctuations in the intensity of the irradiating light beam produce noise.